Remodeling of regulation of cell growth by glycogene and its application.

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Although the importance of glycosylation of components on the cell membrane is widely accepted, the relationship with cell growth has been only poorly investigated.We remodeled the sugar chains on the cells by transfecting PC 12 cells with rat beta- 1, 4-N- acetlylglucosamyltransferase III gene (GnT III) and effects of them on the cellular responses to the nerve growth factor (NGF) were examined.The results show that branch structure, a product of the gene, was found in GnT III-transfected PC 12 cells.However, no change in the growth rate or neurites formation was observed.When effects of NGF on Trk, a NGF receptor, was investigated, tyrosine phosphotylation, which occurs in control cells, was not observed.Moreover, dimerization essential for signal transduction to nucleus did not occur.Then we transfected B 16 melanoma, a line commonly used for metastasis, NIH3T3, and CHOK1 cells with EGF receptor and GnT III cDNAs by electroporation and selected neomycin-resistant cells.Several clones which highly express GnT III were isolated.The sugar chains of the EGF receptor was modified with bisecting GlcNAc structure and dysfunction of cellular response to EGF stimuli was observed.Currently we are investigating the MAP kinase cascade downstream of the EGF receptor signaling.